Leakage Resilient Encryption Scheme for Side-Channel Attack Protection
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Solution Overview
Problem
Existing cryptographic solutions struggle to effectively protect against side-channel attacks on unprotected hardware, particularly in scenarios where switching to protected hardware is costly or impractical.
Innovation Solution
The implementation of a Leakage Resilient encryption scheme using a Leakage Resilient Key Derivation Function (LR-KDF) that generates unique keys for each message from a master key, combined with a double Output FeedBack (OFB) encryption method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protected hardware is used to defend against side-channel attacks, then security against attacks is improved, but device cost and complexity increase significantly
Solution Approach 1:
The patent introduces a mediator layer (the masking function and random values) between the cryptographic key and the encryption operation. This intermediary prevents direct observation of the key through side-channel attacks, as the actual key material is never exposed to the encryption circuitry. Instead, the key is combined with random masking values to create intermediate representations that do not reveal key information through power consumption or electromagnetic emissions.
Solution Approach 2:
The patent extracts the secret key material from the encryption process by using a key derivation function that separates the master key from the actual encryption operations. The master key is kept secure and never directly used in encryption, instead deriving intermediate keys that are used in the encryption process. This extraction prevents attackers from observing the master key through side-channel attacks on the encryption circuitry.
2Reliability
If protected software implementation is used to defend against side-channel attacks, then security against attacks is improved, but reverse engineering protection is compromised and performance decreases
Solution Approach 1:
The patent performs preliminary actions by pre-computing masking values and preparing intermediate representations before the actual encryption operation. The key derivation function generates intermediate keys in advance, and random masking values are prepared beforehand. This preliminary preparation allows the main encryption operation to proceed efficiently without repeated key derivation or masking computations during the critical encryption path.
3Reliability
If key derivation function is used to generate unique keys for each message, then resistance to side-channel attacks is improved, but computational overhead increases
Solution Approach 1:
The patent implements periodic action by structuring the key derivation function to operate in regular, predictable intervals or stages. The KDF processes the master key through a series of standardized transformations (such as hash iterations or block cipher applications) in a periodic manner. This structured periodic processing optimizes the key derivation time by eliminating irregular computational patterns that could waste time while maintaining the security benefits of unique key generation for each message.
Data Source
AI summary
Encryption of data using a cryptographic device is protected. The protecting includes generating a first output of a first branch by encrypting a constant using a key, and generating a first output of a second branch by encrypting a constant using a key. The first output of the first branch, the first output of the second branch, and a first portion of plaintext data are XORed, generating a first portion of cypher text. A second output of the first branch is generated by encrypting the first output of the first branch using a key, and a second output of the second branch is generated by encrypting the first output of the second branch using a key. The second output of the first branch, the second output of the second branch, and a second portion of plaintext data are XORed, generating a second portion of cypher text.